The average daily sunspot numbers dropped this week, from 83.1 to 56, while the average daily solar flux declined from 118.9 to 101.4. Sunspot numbers for September 13-19 were 44, 44, 53, 77, 51, 61 and 62, with a mean of 56. The 10.7 cm flux was 99.1, 100.5, 97.5, 97.3, 101.5, 104.3 and 109.8, with a mean of 101.4. The estimated planetary A indices were 6, 5, 6, 7, 6, 8 and 14, with a mean of 7.4. The estimated mid-latitude A indices were 6, 5, 5, 7, 6, 7 and 13, with a mean of 7

The latest forecast shows predicted solar flux at 115 on September 21-22, 120 on September 23-25, then 125 on September 26-27, 130 on September 28, and peaking at 140 on September 29-October 1. On October 2, it then drops to 135, 130 on October 3-5, 125 on October 6-7, 120 on October 8, and down to 115 on October 8-9. Flux values then dip below 100 on October 14-16, and peak again around 140 on October 25-28. The predicted planetary A index is 12 on September 21-22, 10 on September 23, 5 on September 24-28, back to 10 again on September 29, 5 on September 30-October 2, 10 on October 3, 8 on October 4-5, and down to 5 on October 6-11.

Carol Milazzo, KP4MD/W6, in Citrus Heights, California, wrote in about WSPR mode for weak signal work on 2 meters: “California 2 meter WSPR study group stations on 144.4905 MHz can be heard throughout the state of California from Redding at the north end of the Central Valley down to San Diego. Joe Taylor’s K1JT, WSPR mode allows stations with modest power and antennas to participate in weak signal VHF propagation experiments. Some of our data is posted here.”

Scott Avery, WA6LIE, of Salinas, California, writes: “I was very disappointed in last week’s ARRL VHF/UHF contest. We got skunked on 6 meters to local only, but we worked all the locals on 2 meters on up. A few weeks ago, I started experimenting with WSPR. It is interesting to see what your station hears -- and who hears you. Anyway, most of my WSPR work has been on 2 meters. Though WSPR is not too popular yet, I have had some pretty amazing results. Most of the stations are in the San Francisco Bay area, but a few new ones popped up in Los Angeles and San Diego area. Beaming south, I still hear a few stations 100 miles-plus to the north. To the south, N3IZN in Fallbrook is working me at 340 miles away, as is N6KOG at 387 miles several times a day (via tropo?). It would be nice to see more WSPR stations up on VHF/UHF.”

Rich Zwirko, K1HTV, of Amissville, Virginia, wrote on September 14 about what happenedoin September 6: “I got up early and called CQ on CW on 144.330 MHz. An announce message was made of the DX Cluster. I logged into the ON4KST.org 144/432 website and notified the guys of my transmissions. A suggestion was made that I transmit on JT65A, which I started to do on 144.325 MHz. Three Irish stations and G4LOH participated on the European end of the path. Eventually, when I had to stop transmitting at 1200, VE1SKY in Nova Scotia and K1TEO in Connecticut joined in the test. But as far as I know, there were no trans-Atlantic contacts.

Dave Clemons, K1VUT, of Middleboro, Massachusetts (FN41), wrote: “On September 8 during the ARRL VHF Contest on 6 meters, I worked LU9EHJ in Argentina and PY1RO in Brazil. I believe these might have been a combination of trans-equatorial propagation and E-skip, since it appears that the QSOs might not have been equal distance from the equator on both ends (or I could be geographically challenged). Either way, it was very nice to get that far south on 6 meters.”

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.